1. Technical Field
This invention relates generally to rotary machines such as gas turbine engines and particularly to a seal for sealing a rotor of such a machine to a stator therefore.
2. Background Information
It is a common practice to seal the stator of a rotary machine such as a gas turbine engine to a rotor thereof to control the flow of working fluid through the machine. For example, it is a known practice to seal the radially inner ends of flow directing vanes in the stator of a gas turbine engine to the engine's rotor to prevent working fluid flowing through the engine from flowing inwardly around the radially inner ends of such vanes thereby bypassing the flow directing airfoil surfaces of such vanes. It is a challenge to provide seals which will effectively seal a gas turbine engine stator to the rotor thereof under a wide range of operating conditions which the engine experiences. For example, changing rotor speeds result in diametrical rotor expansion and contraction as the rotor speeds increase and decrease under normal operating conditions. Also, changing thermal operating conditions of the engine may result in differential radial expansion and contraction of the stator and rotor due to differing rates of thermal expansion and contraction of the materials employed therein. Accordingly, it will be appreciated that seals which seal the stator to the rotor must accommodate such radial expansion and contraction of the engine rotor and stator due to such variations in thermal and dynamic operating characteristics.
There are several known arrangements for sealing gas turbine engine rotors to stators thereof in a way which will accommodate expansion and contraction of the rotors and stators due to variations in dynamic and thermal operating conditions. For example, it is a known practice to pin a nonrotating component of the seal to the stator and provide the nonrotating seal component and stator with splines to allow that seal component to move radially with respect to the stator in response to changes in thermal and dynamic operating conditions. However, such pinned and spline connections take up a significant amount of room within the engine and may interfere with the optimal handling of working fluid flowing through the engine. Accordingly, arrangements are continually sought for sealing turbomachine (such as gas turbine engine) rotors to the stators thereof in a manner which will accommodate radial expansion and contraction of the rotor and stator due to diverse thermal and dynamic operating conditions in a compact manner which minimizes the space taken up by the seal and the resulting interference by mounting hardware for the seal with the optimal handling of working fluid flow through the machine